Pins are 3D markup that you can use to indicate an area of your model that’s important to analyze. When you add a pin, you can also add comments to the pin that describe what needs to be reviewed. Pins and comments are always associated with snapshots in one of the following ways:
- When you add a pin, and you do not have an existing snapshot selected, a new snapshot
with the pin 
and comment 
is created. - If you select an existing snapshot, when you add a pin, that pin and comment are added to the selected snapshot.
Your pins and comments are private in your model file, even if you share the model with others. However, you can easily share this information with others by adding the snapshot with your pin to a story. All collaborators with whom you share the story can see your pin and respond with comments.
For more information about stories, see Introduction to stories.